A method for controlling the desolvation phase of large-scale ultra-high-strength high-alloy aluminum alloy plates

Abstract

A method for controlling the dissolution phase of a large-sized ultra-high strength and high-alloyed aluminum alloy plate, specifically relates to a method for controlling the dissolution phase of a large-sized ultra-high strength and high-alloyed aluminum alloy plate. The present invention aims to solve the problem that the existing large-sized ultra-high strength and high-alloyed aluminum alloy plate produces precipitation of dissolution phase after quenching after solution heat treatment, reduces the concentration of supersaturated solid solution, and seriously affects the comprehensive performance of the plate in the final state. The present invention shortens the time for the plate to be transferred from the heat treatment furnace to the quenching medium) and controls the cooling intensity of the quenching zone (including process parameters such as the fluidity of the quenching medium and the temperature of the quenching medium), thereby minimizing the dissolution of the phase in the supersaturated solid solution during the quenching transfer of the plate, ensuring the final comprehensive performance of the 7xxx ultra-high strength and high-alloyed aluminum alloy plate with a thickness of no more than 102 mm, meeting the standard requirements, and significantly improving the fracture toughness, spalling and stress corrosion performance of the plate. The present invention is used in the field of metal material technology.

Description

Technical Field

[0001] The invention belongs to a method for controlling the desolvation phase of a large-size ultra-high-strength high-alloyed aluminum alloy plate. Background Art

[0002] The purpose of quenching cooling is to quickly cool the alloy to a relatively low temperature (usually room temperature) so that the solid solution formed during solution treatment is fixed into a solid solution in which both solute and vacancy are supersaturated at room temperature. Generally speaking, during the quenching process of the plate, the fastest quenching cooling rate can achieve the highest strength of the plate and the best match of strength and toughness, thereby improving the stress corrosion resistance of the plate.

[0003] During the quenching process after the plate is taken out of the roller hearth furnace, the natural cooling of the plate is completely achieved by the heat exchange between the water sprayed on the surface and the plate. During the cooling process, the cooling rate difference between the surface and the core of the plate is inevitable. For the ultra-high strength and high alloyed 7xxx alloy with high quenching sensitivity, the interlayer performance difference of each thickness layer of the plate will be more obvious. In addition, the precipitation of the supersaturated solid solution during the time period from the plate being taken out of the furnace after solution heat treatment to the plate being quenched into water, the spray cooling process, and the temperature recovery after quenching water, reduces the concentration of the supersaturated solid solution, reduces the aging potential, and seriously affects the improvement of the comprehensive performance of the plate in the final state. Summary of the invention

[0004] In order to solve the problem that the existing large-sized ultra-high strength and high alloy aluminum alloy plates produce precipitation of dissolution phases after quenching after solution heat treatment, reduce the concentration of supersaturated solid solution, and seriously affect the comprehensive performance of the final state of the plate, the present invention provides a large-sized ultra-high strength and high alloy aluminum alloy plate dissolution phase control method.

[0005] A method for controlling the desolvation phase of a large-scale ultra-high-strength high-alloyed aluminum alloy plate of the present invention is as follows:

[0006] The 7xxx alloy ultra-high strength high alloy aluminum alloy sheet is hot-rolled and trimmed, and then loaded into a roller hearth quenching furnace for solid solution heat treatment, and after the solid solution heat treatment is completed, it is transferred to a quenching medium for quenching, so as to obtain a quenched sheet;

[0007] The pressure of the quenching medium in the nozzle is 1.6 bar to 2.9 bar, and the temperature of the quenching medium is 5° C. to 38° C.; the speed at which the plate is transferred from the solution furnace to the quenching zone is 6 m / min to 16 m / min.

[0008] Beneficial effects of the present invention:

[0009] The strong quenching technology after solution treatment of the plate of the present invention: "rapid transfer out of the furnace - roller bottom spray quenching strong cooling" retains the solid solution concentration to the maximum extent, which is beneficial to the synergistic improvement of the comprehensive performance of the plate. Under industrial conditions, innovative large-scale ultra-high strength and high-alloyed aluminum alloy plate desolvation phase control technology has been developed, which is suitable for the industrial production of 7xxx large-scale plates. The comprehensive performance matching of "strength-elongation-fracture toughness-stress corrosion and exfoliation corrosion resistance-high cycle fatigue" of mass-produced 7B65-T7451 and 7B65-T7751 thick plate products has met the requirements of relevant domestic technical indicators and is superior to other similar products. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of the control process of the present invention;

[0011] Figure 2 It is the SEM morphology of the solution phase of the 7XXX alloy plate under different quenching conditions in Example 1, Figure a is the example, and Figure b is the control. DETAILED DESCRIPTION

[0012] Specific implementation method 1: In this implementation method, a method for controlling the desolvation phase of a large-scale ultra-high strength and high alloy aluminum alloy plate is as follows:

[0013] The 7xxx alloy ultra-high strength high alloy aluminum alloy sheet is hot-rolled and trimmed, and then loaded into a roller hearth quenching furnace for solid solution heat treatment, and after the solid solution heat treatment is completed, it is transferred to a quenching medium for quenching, so as to obtain a quenched sheet;

[0014] The pressure of the quenching medium in the nozzle is 1.6 bar to 2.9 bar, and the temperature of the quenching medium is 5° C. to 38° C.; the speed at which the plate is transferred from the solution furnace to the quenching zone is 6 m / min to 16 m / min.

[0015] Specific implementation method 2: This implementation method is different from the specific implementation method 1 in that the thickness of the 7xxx alloy ultra-high strength high alloy aluminum alloy plate is ≤ 102 mm. The rest is the same as the specific implementation method 1.

[0016] Specific implementation method 3: This implementation method is different from specific implementation method 1 or 2 in that the thickness of the 7xxx alloy ultra-high strength high alloy aluminum alloy plate is 80 mm. Other aspects are the same as specific implementation method 1 or 2.

[0017] Specific embodiment 4: This embodiment is different from specific embodiments 1 to 3 in that the speed of the plate from the solution furnace to the quenching zone is 16 m / min. The rest is the same as specific embodiments 1 to 3.

[0018] Specific implementation method 5: This implementation method is different from specific implementation methods 1 to 4 in that the speed of the plate from the solution furnace to the quenching zone is 6.5 m / min. The rest is the same as specific implementation methods 1 to 4.

[0019] Specific embodiment 6: This embodiment is different from specific embodiments 1 to 5 in that the quenching medium is water, the quenching water pressure is 1.6 bar to 2.1 bar, and the cooling water temperature is 24° C. The rest is the same as specific embodiments 1 to 5.

[0020] Specific embodiment 7: This embodiment is different from specific embodiments 1 to 6 in that the quenching medium is water, the quenching water pressure is 2.5 bar to 2.9 bar, and the cooling water temperature is 26° C. The rest is the same as specific embodiments 1 to 6.

[0021] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that the amount of alloying elements added to the 7xxx alloy ultra-high strength high alloyed aluminum alloy plate is 12 wt %. The rest is the same as specific embodiments 1 to 7.

[0022] The content of the present invention is not limited to the content of the above-mentioned embodiments. The combination of one or several specific embodiments can also achieve the purpose of the invention.

[0023] Embodiment 1: This embodiment of a large-scale ultra-high strength high alloy aluminum alloy plate desolvation phase control method is:

[0024] 7B65-T7751 alloy 25mm thick plate, after hot rolling trimming, was loaded into a roller hearth furnace for solution treatment (471-482℃ / 90min), the quenching transfer speed of the plate was 16m / min, the quenching water pressure was controlled at 1.6bar-2.1bar, and the cooling water temperature was 24℃. The properties of the plate after aging treatment are shown in Table 1.

[0025] Table 1 Properties of 7B65-T7751 alloy plate after quenching using the technology of this embodiment

[0026]

[0027] Figure 1 is a schematic diagram of the method of the present invention;

[0028] Figure 2 The SEM morphology of the desolvated phase of the 7XXX alloy plate under different quenching conditions in Example 1, Figure a is the example, and Figure b is the control. The desolvated phase of the plate quenched structure controlled by the quenching technology of this example is significantly reduced.

[0029] Embodiment 2: In this embodiment, a method for controlling the desolvation phase of a large-sized ultra-high strength high alloy aluminum alloy plate is as follows:

[0030] 7B65-T7451 alloy 80mm thick plate, after hot rolling trimming, was loaded into a roller hearth furnace for solution treatment (471-482℃ / 240min), the quenching transfer speed of the plate was 6.5m / min, the quenching water pressure was controlled at 2.5bar-2.9bar, and the cooling water temperature was 26℃. The properties of the plate after aging treatment are shown in Table 2.

[0031] Table 2 Properties of 7B65-T7451 alloy plate after quenching using the technology of this embodiment

[0032]

[0033] The comprehensive performance of plates with the same thickness specifications has been greatly improved compared with 7050 and 7065 alloys. The comparison is shown in Tables 3 and 4.

[0034] Table 3 Comparison of tensile performance index of 7B65 sheet with tensile performance standard of 7050 and 7065 sheet

[0035]

[0036]

[0037] Table 4 Comparison of fracture toughness index of 7B65 plate and fracture toughness standard of 7050 and 7065 plate

[0038]

[0039] The exfoliation corrosion requirements of 7B65 plates are "meeting or better than EA grade", and the stress corrosion resistance requirements are "no cracking after 30 days of testing when a load of 310MPa is applied". These are significantly improved compared to the exfoliation corrosion requirements of 7050 and 7065 plates, which are "meeting or better than EB grade", the stress corrosion resistance requirements of 7050 plates, which are "no cracking after 30 days of testing when a load of 241MPa is applied", and the stress corrosion resistance requirements of 7065 plates, which are "no cracking after 30 days of testing when a load of 172MPa is applied".

[0040] The high cycle fatigue requirement of 7B65 plate is "an average of 120,000 for four pieces under a maximum load stress of 310 MPa", which is significantly higher than the high cycle fatigue requirement of 7050 plate "an average of 120,000 for four pieces under a maximum load stress of 241 MPa".

[0041] The alloy element addition amount of 7B65 plate is 12wt%, that of 7050 plate is 10.82wt%, and that of 7065 plate is 11.55wt%.

[0042] From the comparison of strength and toughness data, corrosion performance and high cycle fatigue index requirements in Tables 1-4, it can be seen that after quenching using the technology of the present invention, the precipitation of the desolvated phase during the quenching process is effectively controlled, the concentration of the supersaturated solid solution is increased, and the performance of the plate is greatly improved compared with conventional 7050 alloy plates and internationally advanced 7065 alloy plates, achieving a significant improvement in the comprehensive performance of 7xxx ultra-high strength and high alloying plates, with significant results.

[0043] The present invention reduces the precipitation of supersaturated solid solution during the quenching and cooling of the plate by effectively controlling the process of transferring the 7xxx ultra-high strength and high alloy plate from the heat treatment furnace to the quenching medium, the flow rate of the quenching medium during the plate quenching, the temperature of the plate quenching medium, and the residence time in the cooling zone, thereby maximizing the concentration of the supersaturated solid solution obtained by the solution treatment of the plate, increasing the aging strengthening potential, effectively improving the comprehensive performance of the ultra-high strength and high alloy plate, and realizing the upgrading of the comprehensive performance of the 7xxx alloy plate.

Claims

1. A method for controlling the desolvation phase of a large-scale ultra-high strength and high alloy aluminum alloy plate, characterized in that: The method is: The 7xxx alloy ultra-high strength high alloy aluminum alloy sheet is hot-rolled and trimmed, and then loaded into a roller hearth quenching furnace for solid solution heat treatment, and after the solid solution heat treatment is completed, it is transferred to a quenching medium for quenching, so as to obtain a quenched sheet; The pressure of the quenching medium in the nozzle is 1.6 bar to 2.9 bar, and the temperature of the quenching medium is 5° C. to 38° C.; the speed at which the plate is transferred from the solution furnace to the quenching zone is 6 m / min to 16 m / min.

2. The method for controlling the desolvation phase of a large-size ultra-high strength and high alloyed aluminum alloy sheet according to claim 1, characterized in that: The thickness of 7xxx alloy ultra-high strength high alloyed aluminum alloy plate is ≤102mm.

3. The method for controlling the desolvation phase of a large-sized ultra-high strength and high alloyed aluminum alloy sheet according to claim 1, characterized in that: The thickness of 7xxx alloy ultra-high strength high alloyed aluminum alloy plate is 80mm.

4. The method for controlling the desolvation phase of a large-scale ultra-high strength and high alloyed aluminum alloy sheet according to claim 1, characterized in that: The plate is transferred from the solution furnace to the quenching zone at a speed of 16 m / min.

5. The method for controlling the desolvation phase of a large-size ultra-high strength and high alloyed aluminum alloy sheet according to claim 1, characterized in that: The plate is transferred from the solution furnace to the quenching zone at a speed of 6.5 m / min.

6. The method for controlling the desolvation phase of a large-size ultra-high strength and high alloyed aluminum alloy sheet according to claim 1, characterized in that: The quenching medium is water, the quenching water pressure is 1.6 bar ~ 2.1 bar, and the cooling water temperature is 24 ° C.

7. The method for controlling the desolvation phase of a large-size ultra-high strength and high alloyed aluminum alloy sheet according to claim 1, characterized in that: The quenching medium is water, the quenching water pressure is 2.5bar~2.9bar, and the cooling water temperature is 26℃.

8. The method for controlling the desolvation phase of a large-size ultra-high strength and high alloyed aluminum alloy sheet according to claim 1, characterized in that: The alloying element addition amount of 7xxx alloy ultra-high strength high alloyed aluminum alloy sheet is up to 12wt%.

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